Use explicit PVC selectors for Cassandra

Using release label only can result in claiming Persistent Volume with
mismatched Cassandra version (2.1.20 vs. 3.11.3 as of writing this
patch).

Issue-ID: OOM-1592
Change-Id: I9f534982f6ae91347b17676b1223d397ac28953d
Signed-off-by: Pawel Wieczorek <p.wieczorek2@samsung.com>
diff --git a/kubernetes/aai/charts/aai-cassandra/templates/statefulset.yaml b/kubernetes/aai/charts/aai-cassandra/templates/statefulset.yaml
index 4a8ae39..a576eba 100644
--- a/kubernetes/aai/charts/aai-cassandra/templates/statefulset.yaml
+++ b/kubernetes/aai/charts/aai-cassandra/templates/statefulset.yaml
@@ -127,5 +127,6 @@
             storage: {{ .Values.persistence.size | quote }}
         selector:
           matchLabels:
+            app: {{ include "common.name" . }}
             release: "{{ .Release.Name }}"
   {{- end }}